In general, a wiring is formed on a substrate such as a semiconductor wafer or a liquid crystal substrate to form a circuit on a surface of the substrate. The wiring is typically made of, instead of aluminum, copper having low electric resistance and high reliability. Since, however, copper tends to be easily oxidized as compared to aluminum, it is required to plate a surface of the copper wiring with a metal having high electromigration resistance in order to suppress the surface of the copper wiring from being oxidized.
For example, a plating process is performed by supplying an electroless plating liquid onto the surface of the substrate on which the copper wiring is formed. Conventionally, such an electroless plating process is performed by a batch-type processing apparatus, in general. In the electroless plating process, in order to form a plating film by incurring an oxidation-reduction reaction in the vicinity of a surface of a wafer, it is desirable to stand the wafer without being shaken during the film forming process. For this reason, when performing the electroless plating process in the batch-type processing apparatus, a film forming rate of the plating film is controlled by adjusting a temperature of the plating liquid, a concentration of the plating liquid and a film forming time. Further, in consideration of the structure of the batch-type processing apparatus, even if it is attempted to move the wafer in the plating liquid, the wafer would be shaken only several centimeters. Thus, when the conventional batch-type processing apparatus is used, it may be difficult to improve a reaction rate of the plating liquid over a current level.
Patent Document 1: Japanese Patent Laid-open Publication No. 2009-249679
Patent Document 2: Japanese Patent Laid-open Publication No. 2001-073157